Method of manufacturing and assembling hydraulic pumps



Dec. 9, 1952 SCHULTZ 2,620,553

METHOD OF MANUFACTURING AND ASSEMBLING HYDRAULIC PUMPS Filed April 15, 1949 Patented Dec. 9, 1952 METHOD OF MANUFACTURING AND ASSEM- BLING HYDRAULIC PUMPS Harold B. Schultz, South Bend, Ind., assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application April 15, 1949, Serial No. 87,806

(Cl. 29l56.4)

4 Claims.

= This invention relates to pumps and more particularly to a method of pump manufacture and assembly of the same.

It is a well known fact that the man-hours required in the manufacture and assembly of apparatus using precision parts is often so far out of line that the sale price of the article becomes prohibitive, thus rendering the article unsaleable in a competitive market. That is, in a competitive market, the sale price of the commodity usually dictates its popularity, notwithstanding quality, performance, etc.

It is, therefore, an object of the present invention to provide means for controlling the concentricities of the parts during manufacture and assembly of the article.

Another object of the invention resides in the provision of a prescribed sequence for machining and assembling parts for a hydraulic pump or motor in a minimum of man-hours. A still further object of the invention is to introduce a procedure for machining and assembling the parts of a pump or motor that will be conducive to the utmost accuracy.

It is an important object of the invention to provide'a hydraulic pump or motor of the type described, which is simple in construction and eficient in operation.

The above and other objects and features of the invention will be apparent from thefollowing description of the apparatus taken in connection with th accompanying drawing which forms a part of this specification and in which:

Figure l is an exploded view of the device of the invention with the parts shown in perspective;

Figure 2 illustrates the device of the invention in position on a fixture for the initial step in r the assembly;

Figure 3 illustrates the device in position on a fixture during an intermediate step in the assembly; and

Figure 4 shows in perspective one of the gage blocks of Figure 2.

Referring now to Figure l of the drawing the reference numeral I6 designates a gear pump or motor housing provided with a pair of overlapping parallel bores l 2 and I4 forming a chamberyC. Passages l6 and 18, provide inlet and outlet openings respectively, for connecting the chamber C to the exterior of the housing Ill. The inlet and-outlet passages l6 and I8 terminate within the chamber in diametrically opposite locations. The openings of the passages within the chamber are located in the vertices 26 and 22 of the chamber wall formed at the intersection of the overlapping bores. A pair of gears 24 and 26 are arranged in the bores 12 and I4 in meshing engagement. The gears 24 and 26 are fixedly secured to shafts 28 and 36 respectively, which are carried in bushings or bearings 32 and 33, accurately fitted into opposite ends of the bores I2 and I4. The shaft 30 is equipped with a slot 34 at one of its ends for connecting the pump to -a driving source, not shown. Of course, if used as a motor the shaft 36 can be connected to a device, not shown, to be driven. The bores l2 and I4 are closed at their ends by cover plates 36 and 38, having bolt holes 46 and 42, respectively, located at strategic positions around the cover plates. These bolt holes 40 and 42 are aligned with bolt holes 44 in the housing for receiving bolts, not shown, which hold the device in assembled relationship. The cover plate 38 is furnished with inlet and outlet openings 46 and 48 which register with the openings l6 and I8 respectively of the housing, Ill. The cover plate 36 is bored through at 56 to accommodate the shaft 30 which has its slotted end 34 extending exteriorly of the chamber C.

When the device is used as a pump the shaft 30 is rotated in the direction of the arrow thus drawing liquid into the chamber C via the passages 46 and i6. The liquid is carried around the interior of the bores in the pockets or spaces formed between the gear teeth, and forced out of the chamber through the pasages l8 and 48. It is quite evident that if the pump is to have good volumetric efficiency the working parts must be accurately fitted so that there will be a minimum of leakage. To this nd I have established a definite procedure for fitting and assembling the parts into place in a minimum of time and with the highest degree of accuracy.

- To aid in the assembly of the device a base 66, having a perfectly flat surface 62 is provided, on which a set of gage blocks 64 and 66 are placed. The gage blocks 64 and 66 which are of identical geometry, are formed with parallel surfaces 68 and 10, and I2 and 14 respectively. Each of the gage blocks has a segment removed therefrom equal in area to the area of the overlapping portions of the bores to thereby form fiat parallel faces 16 and 18 adapted to be arranged in abutting relatoinship when inserted in the housin as shown in Figure 2. The thicknesses of the gage blocks 64 and 66 are identical. That is. the heights between the parallel faces 68 and II! and 12 and 74 are the same. These heights are equal to the width W of the gears 24 and 26, plus the allowable clearance between the gears and the bushings 32 and 33, plus the width We of the bushings, as measured along their axes. The gage blocks 64 and 66 may be fastened to the fixture or base 66 or merely laid on the base and unattached, as shown in Figure 2. These gage blocks may be integral instead of separate, as shown.

With the gage blocks in their proper positions on the base 60 the housing I is lowered over the blocks so that face D of the housing rests on the flat surface 62. The bushings 32 are now pressed into the open ends of the bores so that the bushings rest flatly on the gage blocksas best shown in Figure 2. The upper or outer sides of the bushings 32 and face E of the housing are surface ground. The gage blocks 64 and are now removed and the sub-assembly turned over on its face E on base 89, see Figure 3. A second set of gage blocks 82 and 84 are inserted into the bores l2 and I4 so that they rest against the upper side of the bottom bushings 32, see Figure 3. Except 'for thickness, the geometry of the gage blocks 82 and 84 is the same as that of gage blocks 64 and 65. The gage blocks 82 and 8: 5 are of the same thickness. The thicknesses of the latter two gage blocks 82 and B4 are equal to the width Wg of the gears 24 and 26 respectively, plus the allowable clearance between each gear and its associated bushings. pressed into the other ends of the bores so that The bushings 33 are now lower sides of the bushings rest flatly on the blocks 32 and 24. The outer sides of these upper bushings 33 and the face D of the housing l 9 are surface ground. Both faces D and E have now are flush with the housing. The cover plates 35 i and 38 are now assembled to the housing. I

Although this invention has been described in connection with certain specific embodiments, the principles are susceptible of numerous other applications that will readily occur to persons skilled in the art.

Having thus described the various features of the invention, what I claim as new and desire to secure by Letters Patent is:

l. The method of assembling a hydraulic pump or motor which comprises pressing a first set of bushings a predetermined distance into one end of each of a pair of overlapping parallel bores in the pump or motor housing, surface grinding said housing flush, removing one set of bushings, inserting a set of gears into the bores so that the axis of one of said gears is coextensive with the axis of one of said bores and the axis of said other gear is coextensive with the axis of said other bore, repressing said removed set of bushings back into the ends of the bores from which the bushings were removed, and assembling cover plates on said housing.

3. The method of assembling a hydraulic pump or motor which comprises inserting a first set of gage blocks into one end of each of a pai of overlapping parallel bores in the pump or motor housing, pressing a first set of bushings into the other ends of said pair of bores and against said gage blocks, surface grinding said first set of bushings flush with the housing, removing said first set. of gage blocks and inserting asecond' set of gage blocks so that they abut the inner side of said first setv of bushings, pressing a second set of bushings into the said one end of each of said pair of bores and against said second set of gage blocks, surface grinding said second set of bushings flush with the nous-,- ing', removing one set ofbushings and the second set of gage blocks, inserting a gear in each of the bores, repressing said removed set of bushings back into the ends of the. bores from which said bushings werev removed, and securing cover plates to said housing.

4. The method of assembling a hydraulic gear pump or motor which comprises the steps of placing the pump or motor housing on a flat surface so that the bores for the gears are at right angles to said surface, inserting a first set of gage blocks into one end of the respective bores so that the gage block in each bore rests on said flat surface, pressing a first set of bushings into the other ends of the bores until said bushings engage their associated gage block, surface grinding said first set of bushings and the housing fi'ush, removing said first set of gage blocks, inserting a second set of gage blocks into the bores so' that said gage blocks rest on the inner ends of their associated bushings, then pressing a second set of bushingsinto said other end of the bores and against the second set of gage blocks,

first set of bushings and the housing fiush, in-

serting a gage block into the other ends of said pair of bores so that said gage block rests on the inner sides of said first set of bushings, then pressing a second set of bushings into said other ends of said bores and against the gage block,

surface grinding said second set of bushings and the housing flush, removing one set of said bushings and the gage block, inserting a set' of gears into said bores" so that the axis of one of said gears is coextensive with the axis of t me of said bores and the axis of said other gear is coextensive with the axis of said other bore, repressing said reinoved set of bushings back into the bores, and assembling cover plates on said housing.

2. The method of assembling a hydraulic pump or motor which comprises pressing a first set of bushings a predetermined distance into one end of each of a pair of overlapping parallel bores in the pump or motor housing, surface grinding said first set of bushings and the housing flush, pressing second set of bushings into the other ends of said bores a predetermined distance, surface grinding said second set of bushings-and the surface grinding said second set of bushings and the housing flush, removing one set of bushings and the second set of gage blocks, placing a set 'of gears into the bore in meshing relationship, repressing said removed set of bushings back into the bores, and attaching cover plates to said housing.

HAROLD B. SCHULTZ.

REFERENCES CITED The following references are of recordinthe file, of this patent:

UNITED STATES PA'I'EN'TS 

